Effect of Heat Therapy to Control Pineapple Wilt Virus in Pineapple (Ananas comosos)

Abstract

Pineapple wilt disease is a common occurrence in pineapple cultivations in Sri Lanka. Reddening of leaves, twisting of their tips and wilting of plants are the characteristic symptoms of this disorder. Clostero shaped virus particles measuring about 1400-1800 nm x 12 nm and bacilliform virus particles with dimensions of 133nm x 33 nm were observed in infected samples of wilted pineapple plants under immuno electron microscopy. Furthermore Australian made polyclonal antiserum gave a strong positive colour reaction when tested with wilted pineapple isolates from Sri Lanka. Pineapple slip suckers known to be infected with clostero and bacilliform virus particles associated with mealy bug wilt of pineapple, were heat treated in hot air and water bath at 400,45°,500,55° and 600 C temperatures for varying time durations. Plant survical was drastically reduced at 600 C. A significant observation was that in both methods of treatment, plants subjected to 55° C for 15 minutes, gave negative results during the first month after heat treatment showing it has temporarily suppreseed the virus in the tissues. However Enzyme linked immunosorbent assay, immunosero electron microscopy and polymerase chain reaction methods demonstrated that heat treatment does not elininate permanently, the two types of virus particles present in wilted pineapple plants in Sri Lanka.